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Magnetic structure and exchange interactions in the Heisenberg pyrochlore antiferromagnet Gd2Pt2O7

DOI: 10.1103/PhysRevB.105.094402 DOI Help

Authors: Philip G. Welch (University of Oxford; ISIS Neutron and Muon Facility) , Joseph A. M. Paddison (Oak Ridge National Laboratory) , Manh Duc Le (ISIS Neutron and Muon Facility) , Jason S. Gardner (Oak Ridge National Laboratory) , Wei-Tin Chen (National Taiwan University) , Andrew R. Wildes (Institut Laue-Langevin) , Andrew L. Goodwin (University of Oxford) , J. Ross Stewart (ISIS Neutron and Muon Facility)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 105

State: Published (Approved)
Published: March 2022

Abstract: The Heisenberg pyrochlore antiferromagnet Gd 2 Pt 2 O 7 is one of a series of gadolinium pyrochlore compounds with a variety of B-site cations. Despite the expected simplicity of a spin-only Gd 3 + Heisenberg interaction model, the gadolinium pyrochlore series exhibits various complex magnetic ground states at low temperature. Gd 2 Pt 2 O 7 displays the highest temperature magnetic order of the series with T N = 1.6 K, which has been attributed to enhanced superexchange pathways facilitated by empty 5 d e g Pt orbitals. In this study, we use various neutron scattering techniques on an isotopically enriched polycrystalline 160 Gd 2 Pt 2 O 7 sample to examine the magnetic structure and spin-wave excitation spectrum below T N in order to extract the dominant exchange interactions. We find that the ground-state magnetic structure is the Palmer-Chalker state previously seen in Gd 2 Sn 2 O 7 with an associated gapped excitation spectrum consistent with enhanced exchange interactions between further near-neighbor Gd 3 + ions. We confirm this exchange model with analysis of the magnetic diffuse scattering in the paramagnetic regime using polarized neutrons.

Journal Keywords: Frustrated magnetism; Pyrochlores; Inelastic neutron scattering; Monte Carlo methods; Neutron diffraction

Diamond Keywords: Antiferromagnetism

Subject Areas: Materials, Physics

Instruments: I11-High Resolution Powder Diffraction

Other Facilities: Polaris at ISIS

Added On: 04/03/2022 09:16

Discipline Tags:

Quantum Materials Physics Magnetism Materials Science

Technical Tags:

Diffraction X-ray Powder Diffraction